Medical connectors for intravenous applications often utilize standard luer connectors having a tapered tubular body which fits into a tapered socket or luer adaptor of a second body to provide a frictional seal between two fluid conduits.
In the early embodiments, the luer connector includes a tapered male nose portion adapted to fit within a tapered female receiver, the two pieces being locked together with a threaded hub engagement. The hub was typically rotationally coupled to the male portion so that assembling the luer connector together by twisting the hub resulted in twisting of the male portion, sometimes establishing a reverse torque within one or both of the fluid conduits extending from the connector components. This reverse torque tended to twist the fluid conduits connected to one or both of the connector components which can cause the loss of patency of the IV site, or other complications associated with twisted conduits.
To remedy this situation, the next generation of luer locks incorporated a separate rotatable hub or sleeve having internal ribs for mating with external splines on either the male or female luer connector body. The hub typically slides axially and freely spins over a first one of the luer components and has an internal stop which cooperates with an external stop on the first luer component. When the male and female components are brought together, the hub engages an external projection or thread on the second luer component and, due to the engaging stops, urges the male component into sealing engagement with the female component. Prior hubs assemble onto the male component from the nose or distal end, and are forced over a stop ring or other structure on the tubular male component. Jamming the hub onto the male component in this manner often results in hoop stress fractures of either piece.
The hub on this type of connector may have two axial positions: a distal, freely rotatable position which allows relative hub to first luer component rotation, and a proximal position in which the hub and first luer component are rotationally locked. This rotational coupling is typically provided by internal ribs on the hub engaging projections on the exterior surface of the first luer component when the hub is in the proximal position. See, e.g., U.S. Pat. No. 4,607,868 to Harvey et al. The rotational lock is provided to assist in breaking the luer connection between the tapered male and female surfaces. Indeed, some luer connections are left in place for extended periods of time resulting in the male and female surfaces of the luer connection being essentially glued together.
Although the hub in the prior art connectors is tightened to join the male and female components together, the hub has a tendency to rotate in a reverse direction increasing the risk of disengagement of the medication line. To prevent this from happening, nurses sometimes apply tape over a tightened hub to prevent it from rotating relative to the male and female luer connection.
Another problem with the aforementioned hub-type luer connection arises from the internal ribs on the hub and the external projections on the first luer component to provide rotational locking engagement. The operator occasionally has difficulty sliding the hub proximally over the first luer component to engage the projections because the ribs and projections are circumferentially aligned and in some rotational positions interfere with each other. In addition, the outer diameter of the hub is large enough to interfere with the appropriate percutaneous entrance angle for an I.V. needle, particularly in pediatric applications. The use of hub-type luer connectors on these sensitive applications may be inappropriate, and a simple slip luer is commonly used. This necessitates maintaining an inventory of both types of luer connectors.
Thus there is a need for an improved connector in which the risk of inadvertent hub rotation is minimized by a relatively high anti-rotation friction, and the other limitations of the prior art connectors are overcome. There is also a need for a connector in which the hub can be pulled away from the luer to permit slip connections.